GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC P42 Commercial Chassis 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Scan Tool Does Not Communicate with Electronic Brake Control Module

Step

Action

Value(s)

Yes

No

1

Did you perform the Data Link Communications Systems Check?

--

Go to Step 2

Got to Data Link Communications System Check

2
  1. Inspect the data link connector (DLC). Repair any damaged terminals if required.
  2. Verify that the Scan Tool is firmly connected to the DLC.
  3. Turn the ignition switch to the RUN position.
  4. Attempt scan tool communications with the electronic brake control module (EBCM).

Can communications be established?

--

System OK

Go to Step 3

3
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the vehicle control module (VCM) connector C4 for gasoline engines, or the powertrain control module (PCM) connector C3 for diesel engines.
  3. Disconnect the EBCM connector C1 for P42 vehicles, or C3 for P32 vehicles.
  4. Use a J 39200 DMM in order to measure the resistance on the DLC from terminal 2 to terminal 5.

Is the resistance greater than the specified value?

10M ohms

Go to Step 5

Go to Step 4

4

Locate and repair the short to ground in CKT 1807 (PPL).

Did you complete the repair?

--

System OK

--

5

Use a J 39200 DMM in order to measure the resistance on the DLC from terminal 12 to terminal 5.

Is the resistance greater than the specified value?

10M ohms

Go to Step 7

Go to Step 6

6

Locate and repair the short to ground in CKT 799 (TAN/WHT).

Did you complete the repair?

--

System OK

--

7
  1. Turn the ignition switch to the RUN position.
  2. Use a J 39200 DMM in order to measure the voltage on the DLC from terminal 2 to terminal 5.

Is the voltage less than the specified value?

1.0 V

Go to Step 9

Go to Step 8

8

Locate and repair the short to B+ in CKT 1807 (PPL).

Did you complete the repair?

--

System OK

--

9

Use a J 39200 DMM in order to measure the voltage on the DLC from terminal 12 to terminal 5.

Is the voltage less than the specified value?

1.0 V

Go to Step 11

Go to Step 10

10

Locate and repair the short to B+ in CKT 799 (TAN/WHT).

Did you complete the repair?

--

System OK

--

11
  1. Turn the ignition switch to the OFF position.
  2. Use a J 39200 DMM to measure the resistance of CKT 1807 (PPL) from the DLC terminal 2 to the EBCM.

Is the resistance greater than the specified value?

5.0 ohms

Go to Step 12

Go to Step 13

12

Locate and repair the open in CKT 1807 (PPL).

Did you complete the repair?

--

System OK

--

13

Use a J 39200 DMM in order to measure the resistance of CKT 799 (TAN/WHT) from the DLC terminal 12 to the EBCM.

Is the resistance greater than the specified value?

5.0 ohms

Go to Step 14

Go to Step 15

14

Locate and repair the open in CKT 799 (TAN/WHT).

Did you complete the repair?

--

System OK

--

15
  1. Connect the EBCM.
  2. Connect the VCM (gasoline engines) or the PCM (diesel engines).
  3. Turn the ignition switch to the RUN position.
  4. Install the scan tool.
  5. Attempt to establish communications to the EBCM.

Can communications be established?

--

System OK

Go to Step 1